This invention relates, particularly, to a parallel folding device of a folding machine, in which a parallel single-folded signature can be smoothly transferred between first and second jaw cylinders.
A web rotary press is equipped with a folding machine for cutting a web, which has been dried and cooled after printing, at intervals of a predetermined length, or for folding the web widthwise or lengthwise.
The folding machine has various structures. Among them, for example, there is one having a parallel folding device as shown in FIGS. 3 and 4(a) and 4(b), (see Japanese Utility Model Publication No. 43097/95).
This folding machine has a cut-off cylinder 1, a folding cylinder 2, a first jaw cylinder 3, and a second jaw cylinder 4 which are opposed to each other in contact and rotate in the directions of arrows in the drawing. A web 8, fed by a nipping roller 5, a cross perforation cylinder 6, and a nipping roller 7 in this order, is cut to predetermined dimensions with a cut-off knife (not shown) of the cut-off cylinder 1 to form a signature 9. This signature 9 is parallel folded between a single-folding knife (not shown) of the folding cylinder 2 and a gripper board 10 and a folding jaw 11 of the first jaw cylinder 3. In the case of parallel single folding, the signature 9, as single folded, is transported toward a chopper 14 by a gripper 12 and a gripper pad 13 of the second jaw cylinder 4 (see FIG. 4(a)). In the case of parallel double folding or delta folding, the signature is further parallel folded between a double-folding knife (not shown) of the first jaw cylinder 3 and a gripper board 15 and a folding jaw 16 of the second jaw cylinder 4. As a result, the signature is parallel double folded, and transported toward the chopper 14 (see FIG. 4(b)).
In the drawings, the numerals 17a to 17c denote signature transporting/holding brushes for transfer of the signature 9 between the first jaw cylinder 3 and the second jaw cylinder 4.
The foregoing parallel folding device faces the following problems: When the signature 9, parallel folded once, is transferred from the first jaw cylinder 3 to the second jaw cylinder 4, the front end of the signature bent by a gripping margin of the signature, which has been gripped by the gripper board 10 and the folding jaw 11 of the first jaw cylinder 3 as shown in FIG. 3, is raised by the gripper 12 of the second jaw cylinder 4 and then gripped. If the paper quality of the web is such that the front end of the signature has inherent characteristics, therefore, breakage and curling of the front end of the signature, curling of the entire signature, and mistiming occur, making stable transfer of the signature impossible. During chopper folding at a subsequent step, moreover, such problematical signature 9 exerts adverse influence, deteriorating the accuracy of chopper folding.
Furthermore, the parallel folding device is configured to be able to perform parallel double folding and delta folding, as shown in FIG. 4(b). Thus, when the parallel single-folded signature 9 is transferred as shown in FIG. 4(a), the phenomenon that the signature 9 is carried away toward the first jaw cylinder 3 because of the presence of a space A takes place. As a result, a folding trouble as shown in FIGS. 5(a) to 5(c) occurs, such as a middle fold (the case of FIG. 5(a)), a corner fold (the case of FIG. 5(b)), or cuts in the trailing edge of the sheet (the case of FIG. 5(c)).
The present invention has been accomplished to solve the above-mentioned problems. The object of the invention is to provide a parallel folding device of a folding machine, which can perform parallel double folding and delta folding, and which can smoothly and reliably transfer a parallel single-folded signature between first and second jaw cylinders regardless of paper quality.
To attain the above object, in a parallel folding device of a folding machine, comprising a first jaw cylinder and a second jaw cylinder arranged with circumferential surfaces thereof opposed to and in contact with each other, a belt is passed over a part of the circumferential surface of the first jaw cylinder, and the belt can be switched between a guide position at which the belt guides a front end of a signature from the first jaw cylinder to the second jaw cylinder during gripping change from the first jaw cylinder to the second jaw cylinder, and a retreat position to which the belt retreats from the second jaw cylinder when the signature is folded by the first jaw cylinder and the second jaw cylinder.
According to this feature, parallel double folding and delta folding are possible because of the presence of the second jaw cylinder. Moreover, a parallel single-folded signature can be transferred smoothly and reliably between the first and second jaw cylinders under guidance by the belt regardless of paper quality.
Inwardly of right and left frames, as a pair, of the folding machine, a plurality of rollers are provided transversely below the first jaw cylinder rotatably and parallel to the first jaw cylinder, and the belt is looped between these rollers and the first jaw cylinder.
Thus, stable belt engagement is possible.
A plurality of the belts are provided so as to run along the circumferential surface of the first jaw cylinder in a region in which the first jaw cylinder transports the signature, and each of the belts travels in accordance with the rotation of the first jaw cylinder by a frictional force working between each of the belts and the circumferential surface of the first jaw cylinder.
Thus, drag of each belt is performed smoothly and reliably.
A plurality of annular grooves are provided on the circumferential surface of the first jaw cylinder so as to be out of phase with a gripper board and a folding jaw in a cylinder shaft direction, the belts are passed in the annular grooves along the circumferential surface of the first jaw cylinder, and the depth of the annular groove is set such that the outer peripheral surface of the belt and the circumferential surface of the cylinder form the same peripheral surface.
Thus, occurrence of concave and convex flaws by the belt is avoided, and the quality maintenance of the signature is achieved.
The roller closest to the second jaw cylinder is adapted to be movable toward and away from the second jaw cylinder via bearing members for supporting both shaft ends of the roller, whereby the belt can be switched between the guide position and the retreat position.
Thus, scratches of the belt under varying tension are avoided, and the quality maintenance of the signature is achieved.